Globe Champion 300

[wb8uhz]

 

   Trying to fix a WRL Globe Champion 300. The problem is that I've lost filament voltage only to the initial stages of the Speech Amp. There is no filament voltage for the 6AU6, 12AX7, 6AQ5 and the 6AL5. I've checked the tube sockets, cleaned them and looked for a bad solder connection on the filament string and re-heated  the string, however still no filament voltage. Any suggestions?

Thanks Tim
WB8UHZ

[WQ9E]

Filament feed to the speech amp section is controlled by a switch on the audio gain control, make sure the gain is turned up and if so check for a bad switch section on this control.

[wb8uhz]

 Thank you. That switch seems to work OK when testing with a volt/ohm meter but I'm thinking if I can find one just replace the switch entirely and see if that fixes the problem. What do you think of just bypassing the  switch?

[Steve - K4HX]

Yea, just jumper around it and see what happens. If the fils light up, replace it. If you don't use the Champ on CW, the switch of no use.

[wb8uhz]

  Thanks

  I'll jumper it and see but it works using a VOM.

[ke7trp]

Some champs had a seperate switch below the mic gain.  Some had the switch built into the mic gain POT.

Make sure one tube does not have a dead short in the speech amp by yanking tubes out.

C

[wb8uhz]

 Thanks, yes I have tried other tubes as well but still no filament voltage.

[Jim, W5JO]

Are the filaments lit on the 2E26, the 12AU6, 6CL6?  If so and the wire from that switch beind where the mic gain pot is attached, you may have an open or missing wire connection to where it terminates.

[wb8uhz]

  Jim

Thanks. The 2E26, 809, 6CL6 all have filament voltage but they are supplied by a different tap on the transformer. The speech amp filaments are for the 6AU6, 12AU7, 6AQ5 and 6AL5, none of those light up.

[KA2DZT]

  Jim

Thanks. The 2E26, 809, 6CL6 all have filament voltage but they are supplied by a different tap on the transformer. The speech amp filaments are for the 6AU6, 12AU7, 6AQ5 and 6AL5, none of those light up.

You probably just answered your own question.  A different tap on the xfmr.  Have you tried to measure the filament voltage on the other tap?  It's possible that the xfmr filament winding is open.

Fred

[Jim, W5JO]

Thanks. The 2E26, 809, 6CL6 all have filament voltage but they are supplied by a different tap on the transformer. The speech amp filaments are for the 6AU6, 12AU7, 6AQ5 and 6AL5, none of those light up.

Has the transformer been replaced with a non standard version.  In the standard version there are two 6 volt windings, one for the 809s and the other for the rest of the tubes.  The finals are supplied by a 12 volt winding.  The diagram shows the 6 volt winding in question supplying the 2E26, 6CL6, the 6AU6 in the VFO and the 12AU7 keyer.  Following that is the switch for the audio section on the same winding and the tubes you don't have filament supply on.

If you have a different transformer then that won't be the case and you should measure the voltage on the winding supplying that switch.  If nothing is present then you have a bad transformer or the wire supplying it is disconnected.  You can remove all the tubes in the audio section and used your ohm meter to measure from that switch to each connection for the filament supply on each tube in the audio section. 

From what I am reading, you may have the wire from the switch to that series of tubes either disconnected or missing.

[KM1H]

If the transformer is original it is possibly a broken wire at the switch which I believe then goes to the 6AU6. It was on by one strand on the last one I worked on and then broke off during a QSO but the rig was standing on end and easy to see.

Carl

[N8ETQ]

Yo'


   4X150's are a sweet sub fer the AX-9909's.
"Cheap flat sockets"1. make it the way to go.

1. T195 Mod deck.

/Dan

[ke7trp]

No need to modify the rig.  You can use the Tungsram OS51 ( 6083 or PE1-100 ) tube which is a direct drop in replacement Tube.  They are not expensive and plentiful.  Output power is about the same.  Maybe a tad less.

C

[wd9ive]

5894

[Steve - K4HX]

7094. Only one is needed.

[nq5t]

7094. Only one is needed.

I have two sets of spare AX9909 tubes so probably have enough for at least the rest of my time with my Chump 300.

Out of curiosity, does anyone know if the 7094 requires a different socket than the AX9909? I realize the plate lead needs to be move, and possibly other rewiring.  But I'm having trouble figuring out if a different physical socket is required.

[KM1H]

The 7094 has also reached almost dodo bird status and didnt do very well in the HT-41. Not one of RCA's better ideas.

While a pair of 5894's will do well a pair of 7854's will be better along with their Motorola numbered equivalent which I dont remember offhand.

Carl

[VE3AJM]

Tim WB8UHZ, has used/run the Globe Champion 300 transmitters for many years.

Hopefully he'll get back to the forum/list here, and let us know if he got the filaments lit up on those tubes or tracked down the original problem that he had asked about with that transmitter.

Al VE3AJM

[Jim, W5JO]

The 7094 has also reached almost dodo bird status and didnt do very well in the HT-41. Not one of RCA's better ideas.

While a pair of 5894's will do well a pair of 7854's will be better along with their Motorola numbered equivalent which I dont remember offhand.

Carl

The Motorola part numbers are 97-136-A01 and the generic number is Amperex 8643.  They have a more roubust  plate structure and higher rated HV (750 if memory serves).  I have a pair in my Champ and they work very well.  The 5894 does fine also but the HV rating is about 600 volts.  The 5894 will be ok in the Champ with the normal duty cycle a ham uses.

[KM1H]

Thanks Jim. I just wish the 300 I had here last year didnt already have a half assed 813 conversion when my customer got it. Took a lot of work to get it sorted out as well as efficient on 10M. I already had a couple of NIB 7854's and the Motos also but the sheet metal had all been hacked away.

Carl

[Jim, W5JO]

Thanks Jim. I just wish the 300 I had here last year didnt already have a half assed 813 conversion when my customer got it. Took a lot of work to get it sorted out as well as efficient on 10M. I already had a couple of NIB 7854's and the Motos also but the sheet metal had all been hacked away.

Carl

What a shame Carl, I suppose some previous owner had an 813 and didn't want to buy something else.  The 5894/8643 is a very easy conversion.

[Steve - K4HX]

I was able to turn up three 7094s by just mentioning on the air that I was looking for one. I've seen at least a half dozen at fests since. Yea, they're not common, but not impossible to find. If you get two, you'll have a lifetime supply for use in the Globe Champ.

[KM1H]

Condition and price?

[wb8uhz]

 

    Thanks for all the comments. I found the problem with the GC 300. The Gain switch was bad. I had 6 vots on once side of the switch but not on the other. Both sides of the switch must have the voltage. Of course there was no voltage on the filaments of any of the tubes in the speech amp, those noted. What I have done so far is jump the switch and the filaments are on and using the rig and enjoying it again.

Thanks 73 Tim
WB8UHZ